JSON for Modern C++ 3.8.0

accept
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basic_json
basic_json
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~basic_json
| ## ◆ unflatten()
basic_json nlohmann::basic_json::unflatten | ( |  | ) | const
| inline
  The function restores the arbitrary nesting of a JSON value that has been flattened before using the flatten() function. The JSON value must meet certain constraints: The value must be an object. The keys must be JSON pointers (see RFC 6901) The mapped values must be primitive JSON types. Returns the original JSON from a flattened version Note Empty objects and arrays are flattened by flatten() to `null` values and can not unflattened to their original type. Apart from this example, for a JSON value `j`, the following is always true: `j == j.flatten().unflatten()`. Complexity Linear in the size the JSON value. Exceptions
  type_error.314 | if value is not an object
  type_error.315 | if object values are not primitive
  Example The following code shows how a flattened JSON object is unflattened into the original nested JSON object. 1 #include <iostream> 2 #include <iomanip> 3 #include <nlohmann/json.hpp> 4 5 using json = nlohmann::json; 6 7 int main() 8 { 9 // create JSON value 10 json j_flattened = 11 { 12 {"/answer/everything", 42}, 13 {"/happy", true}, 14 {"/list/0", 1}, 15 {"/list/1", 0}, 16 {"/list/2", 2}, 17 {"/name", "Niels"}, 18 {"/nothing", nullptr}, 19 {"/object/currency", "USD"}, 20 {"/object/value", 42.99}, 21 {"/pi", 3.141} 22 }; 23 24 // call unflatten() 25 std::cout << std::setw(4) << j_flattened.unflatten() << '\n'; 26 } Output (play with this example online):
      {
          "answer": {
              "everything": 42
          },
          "happy": true,
          "list": [
              1,
              0,
              2
          ],
          "name": "Niels",
          "nothing": null,
          "object": {
              "currency": "USD",
              "value": 42.99
          },
          "pi": 3.141
      }
  The example code above can be translated with
      g++ -std=c++11 -Isingle_include doc/examples/unflatten.cpp -o unflatten
See also flatten() for the reverse function Since version 2.0.0 Definition at line 23834 of file json.hpp.

nlohmann::json
basic_json<> json
default JSON class
Definition: json.hpp:2774